This invention relates to blenders as well as pumping apparatus; and more particularly relates to a novel and improved method and apparatus for blending liquids with solid particulate materials, and still further relates to a novel and improved impeller assembly which is conformable for use with blenders as well as centrifugal pumps.
Numerous types of blenders have been devised for intermixing and pumping large volumes of liquid/solid slurries. For example, downhole operations in oil and gas fields, such as, fracturing and cementing operations utilize a blender in which liquids and solids are introduced into a housing, a rotor within the housing, upper and lower impeller portions for intermixing the materials and throwing or advancing the materials outwardly into an annulus surrounding the rotor from which the resultant intermixture or slurry can be discharged into the well. A representative blender is that set forth and described in U.S. Pat. No. 5,904,419 to Jorge O. Arribau, one of the inventors of this invention which patent is incorporated by reference herein (hereinafter referred to as the '419 patent). Other representative patents are U.S. Pat. No. 4,239,396 to Arribau; U.S. Pat. Nos. 3,256,181 and 3,326,536 to Zingg; U.S. Pat. No. 4,850,702 to Arribau and U.S. Pat. No. 4,460,276 to Arribau.
In the '419 patent, liquids were introduced through mixing apertures intermediately between the rotor and annulus for mixing with the solid particles prior to introduction into the relatively high pressure annulus.
There is a continuing but unmet need for a blender of simplified construction which can regulate the balance or mixing point between the solids and slurry in a region radially inwardly of the annulus and be capable of pumping the slurry under a substantially constant pressure over a wide range of mass flow rates. There is similarly a need for an impeller assembly in which impeller vanes are designed to regulate the slurry pressure as well as to prevent liquid or slurry leakage back into the central expeller area. Still further, to decrease the depth of vanes required for the upper impeller region by encouraging more immediate outward flow of sand to achieve the same capacity or mass flow rate as deeper vanes.